The majority of cases of tuberculosis are reactivation of latent infection. Symptoms can be divided into systemic and pulmonary. The most common symptom is fever, followed by night sweats, malaise, fatigue, and weight loss. Productive cough, hemoptysis, and pleuritic chest pain develop as the infection grows in the lungs. When the infection is extensive, shortness of breath may develop. The results of a physical examination are generally not helpful, but rales may be noted over areas of pulmonary infection.4
While the majority of cases of tuberculosis are pulmonary, up to 15 percent of cases will have extrapulmonary manifestations. 4 Common sites include the adrenal glands, bones and joints, gastrointestinal tract, genitourinary tract, lymph nodes, meninges, pericardium, peritoneum, and pleura.
Miliary tuberculosis is the result of wide hematogenous spread during the primary infection, or secondary seeding of the other organs in an immunocompromised host. Fever, cough, weight loss, hepatomegaly, splenomegaly, lymphadenopathy, and signs of multisystem illness should cause one to suspect miliary disease. Laboratory abnormalities include hyponatremia, anemia, thrombocytopenia, and leukopenia. The chest radiograph shows diffuse nodular infiltrates. 4
The most common extrapulmonary site of tuberculosis is the lymphatic system and may involve any of the lymph nodes. Tuberculous adenitis causes symptoms at the site of lymph node enlargement. Fever is usually absent, and the lymphadenopathy is painless. The nodes may develop draining sinuses. Diagnosis is made by lymph node biopsy.4
A tuberculous pleural effusion usually occurs after primary infection, when a subpleural node ruptures into the pleura. 4 Some cases occur during hematogenous spread. Symptoms are usually fever, shortness of breath, and pleuritic chest pain. The fluid is exudative in nature, and analysis may not reveal the organisms on acid-fast staining. A pleural biopsy reveals granulomas.
Pericarditis and peritonitis as a result of tuberculosis are difficult to diagnose and often require biopsy. Complications of tuberculous pericarditis include tamponade and constrictive pericarditis.4
The central nervous system may become seeded during primary infection, leading to several tuberculous (Rich) foci in the meninges, spinal cord, or the brain parenchyma. Rupture of a Rich focus into the subarachnoid space may result in meningitis. In children, the disease is acute, whereas a more indolent course is noted in adults. Fever, signs of meningeal irritation, and cranial nerve deficits are seen. Typical cerebrospinal fluid analysis reveals mononuclear cells and a low glucose level, but early samples may have a predominance of neutrophils.4
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.